In one case, a police armed response unit was called to the home of a sniper last September amid fears he was about to be murdered or abducted by al-Qaeda terrorists.

The Corporal, serving with a Scottish Regiment, was one of a two-man sniping team which shot dead 32 Taliban fighters during a six-month tour of Afghanistan. The soldier – whom this newspaper has agreed not to name – was temporarily forced to leave home his wife and...